when i start my truck in the morning the idle revvs up and then goes right back down and contiounesto do this wit it his about 140 and even sometimes when i stop at a light. the truck is all stock and i was wondering what might cause you idle to jump around

 

the idle should jump to about a thousand if its coldish out, then jump to 1250 and stay until you bump the gas, or it hits 140 degrees. it will continue to idle up until it hits 140 degrees, (if thats what you set the warm up setting to). How many seconds do you have it set up to wait to high idle? I set mine at 30 seconds in the winter, 15 in the summer. might outta wait longer but i ain't to sure on that. If it just jumps around outta random without the throttle bein touched i'd first check the data connection plug from the chip to the truck, then if it still does it i'm not to sure. If the truck never overheats on you, and seems to get up to temp in a fair amount of time then your thermostat should still be good.

 

Seems very odd that the RPM are fluctuating like that. They should rise and stay there until the throttle is touched, or 140* is met. Any codes or other issues while driving?